Expert: Bill Silver - 7/10/2009

Question
I bought a used 200cc 81 honda twinstar which has been running wonderfully except for the throttle sometimes catching, which of course was a problem because the bike was taking off on its own.  I thread the throttle cable more securely thinking this would solve it (previously it'd been dangling on the outside of the handle bars).  Now the bike is flooded with gas whenever I turn it on, revving and backfiring. I fiddled with it some more but still the same result. Any suggestions? Thanks!

Answer
Sasha, I think that a new throttle cable and some carburetor cleaning is in store for this little bike. There may be some old gasoline varnish deposits on the slide that is causing it to stick, too.

Proper cable routing is necessary, so it doesn't try to accelerate when you turn the handlebars either way.

As far as the carburetor is concerned, it sounds like the float valve that maintains fuel level in the carburetor is sticking open or has some dirt/debris in the seat. You can try to drain the carburetor float bowl with the drain screw on the bottom, then see if some fresh fuel flooding back in will wash out the needle/seat for the float valve. If not it has to come off for inspection, cleaning and replacement of parts.

http://www.cmsnl.com/honda-cm200t-twinstar-1981-us_model7280/partslist/E++17.htm...  #2  Use the part numbers on this site to order parts from a local dealer or check Ebay for aftermarket carb kits, as well.


Bill Silver